This specification relates to controlling refrigeration compression systems.
A compressor is a machine which increases the pressure of a compressible fluid, e.g., a gas, through the use of mechanical energy, for instance. Compressors are used in industrial processes in various commercial and industrial applications, for example, in refrigeration, air-conditioning, pipeline, petrochemical, and other applications. Refrigeration compressors (or refrigerant compressors) can be used in refrigeration compression systems to help move heat in refrigeration cycles (or refrigerant cycles). For example, a vapor-compression refrigeration cycle can include feeding a circulating refrigerant (e.g., Freon) into a compressor as a vapor. The vapor is compressed at the compressor and exits the compressor superheated. The superheated vapor travels through a condenser that can cool and remove the superheat and then condense the vapor into a liquid by removing additional heat. The liquid refrigerant goes through, for example, an expansion valve (also called a throttle valve) where its pressure abruptly decreases, causing flash evaporation and auto-refrigeration of, typically, less than half of the liquid. That can result in a mixture of liquid and vapor at a lower temperature and pressure. The cold liquid-vapor mixture then travels through the evaporator coil or tubes and is vaporized by cooling the warm air (from the space being refrigerated) being blown by a fan across evaporator coil or tubes. The resulting refrigerant vapor returns to the compressor inlet to complete the thermodynamic cycle.